G364R mutation of MCM4 detected in human skin cancer cells affects DNA helicase activity of MCM4/6/7 complex
G364R mutation of MCM4 detected in human skin cancer cells affects DNA helicase activity of MCM4/6/7 complex
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DOI：
10.1093/jb/mvv015
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发表时间：
2015-06-01
影响因子：
2.7
通讯作者：
Irie, Daiki
中科院分区：
文献类型：
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作者：
Ishimi, Yukio;Irie, Daiki
在源自人类癌组织的细胞中检测到许多基因突变，但这些突变在癌细胞发展中的作用在很大程度上是未知的。我们检测了在人皮肤癌细胞中检测到的MCM 4的G364 R突变。MCM 4/6/7复合物的形成不受突变的影响。与此概念一致，突变型MCM 4和野生型MCM 4与MCM 6的结合是相当的。在HeLa细胞中表达的这种突变MCM 4的核定位支持这一结论。含有G364 R MCM 4的纯化MCM 4/6/7复合物表现出与含有野生型MCM 4的复合物相似的单链DNA结合水平和ATP酶活性。然而，突变体复合物仅显示出野生型复合物的DNA解旋酶活性的30-50%。当G364 R MCM 4在HeLa细胞中表达时，它被分离成核酸酶敏感的染色质部分，类似于野生型MCM 4。这些结果表明，该突变不影响MCM 2 -7复合物在复制起点上的组装，但它干扰了MCM 2 -7解旋酶功能的某些步骤。因此，这种突变可能通过干扰DNA复制而促进癌细胞的发展。
A number of gene mutations are detected in cells derived from human cancer tissues, but roles of these mutations in cancer cell development are largely unknown. We examined G364R mutation of MCM4 detected in human skin cancer cells. Formation of MCM4/6/7 complex is not affected by the mutation. Consistent with this notion, the binding to MCM6 is comparable between the mutant MCM4 and wild-type MCM4. Nuclear localization of this mutant MCM4 expressed in HeLa cells supports this conclusion. Purified MCM4/6/7 complex containing the G364R MCM4 exhibited similar levels of single-stranded DNA binding and ATPase activities to the complex containing wild-type MCM4. However, the mutant complex showed only 30-50% of DNA helicase activity of the wild-type complex. When G364R MCM4 was expressed in HeLa cells, it was fractionated into nuclease-sensitive chromatin fraction, similar to wild-type MCM4. These results suggest that this mutation does not affect assembly of MCM2-7 complex on replication origins but it interferes some step at function of MCM2-7 helicase. Thus, this mutation may contribute to cancer cell development by disturbing DNA replication.